I love mitmproxy, super easy to use (and to install an interception certificate) and the scripting support makes it very useful for pentesting iOS app traffic etc where I can't easily modify the client
That is because there isn't a good solution. You can get away with repackaging an IPA and hand modifying the binary depending on how they are performing the pinning, but it is always going to be time consuming to do it this way. If you are serious about tinkering you pretty much need a jailbroken device, which is getting harder to maintain by the year.